Taxonomic Notes on a Rare Parasitic Plant Striga gesnerioides (Willd.) Vatke var. minor Santapau and its Comparative Taxonomy with Type var. gesnerioides

: Striga gesnerioides (Willd.) Vatke is a common root parasite found in wild on roots of Euphorbia caducifolia in Indian Thar Desert. Santapau reported its new variety i.e. minor from the Khandala Maharastra. Later on Bhandari M.M. reported this rare var. from N.W. Rajasthan however there are little information is available on it and not much taxonomic description and herbarium sheet as well as digital photographs are available on online platform. Hence the present investigation was done to hunt this rare variety for its proper description and documentation for easy identification. By the current investigation I have successfully re-reported this variety from Indian Thar Desert after three decades from a new site. The newly collected site has been geo tagged for future researchers. Efforts were made to give a proper description and digital photographs of each partin detail, with the comparative taxonomy of its type variety gesnerioides and new keys has also been given for easy identification.


INTRODUCTION
The genus Striga Lour. is a common root hemi-parasite at worldwide and distributed naturally from Tropical & sub tropical old world to Australia. [1]The name Striga comes from Latin derivative [2] which means 'Hag' or 'Witch' perhaps due to the sudden ugly appearance from many crop plant at time of flowering and result in damage of crop.Hence the common name is Witchweed. Previously there are four species of Striga namely S. angustifolia, S. asiatica, S. densiflora and S. gesnerioides were reported from India. [6]Recently two new species of it were discovered namely S. indica [7] and S. kamalii. [8]Among them Striga gesnerioides (Willd.)Vatke is a common root parasite found in wild on roots of Euphorbia caducifolia in Indian Thar Desert and have two varieties namely a type variety generioides and var.minor which was first reported by Santapau from Khandala Maharastra. [9]This variety which has so far been reported only from Khandala and is not uncommonly found growing on the roots of Lepidagathis bandraensis Blatt.Santapau has, however reported it on the roots of Hygrophila serpyllum Anders. in Khandala.Blatter and Hallberg have also observed many forms of S. gesnerioides from Thar Desert which they thought may subsequently prove to be constant varieties. [10]Later on Bhandari, M.M. reported this rare var.from N.W. Rajasthan. [11]However there are little information is available on it and not much taxonomic description and herbarium sheet as well as digital photographs are available offline as well as on online platform which generate difficulties to identify this variety among researchers and taxonomist.Hence the present investigation was done to hunt this rare species for its proper description and proper documentation for easy identification.By the current investigation I have successfully re-reported this variety from Indian Thar Desert after three decades and effort were made to give a proper description and digital photographs of each part in detail with the comparative taxonomy of its type variety gesnerioides.

MATERIAL AND METHODS Survey:
A cumbersome field survey was carried out in Monsoon season 2015-2020 on Hilly tracts of Thar Desert including Jodhpur, Jaisalmer and Barmer district.Since it is a root parasite on Lepidagathis species, hence during survey several Lepidagathis plants were observed for hunting it.The collection site was Geo tagged by Google Earth.
Standard procedures were followed for collection, preservation and herbarium sheet preparation.Digital photos were snapped using Samsung galaxy J 5 prime and Canon EOS 1300 D digital camera.Olympus OIC dissecting microscope was used to

Identification:
The species was identified with the help of authentic specimens in the Herbarium of Botanical Survey of India, Regional Center, Jodhpur, and (BSJO).Online Kew herbarium catalogue, and global biodiversity Information facility, personal collections of M.M. Bhandari in Jai Narain Vyas University, Jodhpur, floras of the Indian Desert (Bhandari, 1990) and Rajasthan (Shetty & Singh, 1991).
Comparative study: A detailed comparative study was done with fresh collections and specimens preserved in Botanical Survey of India regional center Jodhpur (BSJO) and personal collection of M.M. Bhandari.An annual, erect, herbaceous root parasite found on Euphorbia caducifolia.Stem 20-50 cm.tall, un-branched or branched at middle, terete, hairy, soft and magenta colored all over.Leaves reduced, alternate, sessile, adjacent to mother axis, younger ones acuminate and hairy, successively passed into thick acute bract.Flowers in densely crowded terminal spike, diameter 5-5.5 mm at bilateral axis, Bracteate and bracteolate, bract 7 x 2 mm, ciliate at margin, and concave inside, thick raised mid rib on dorsal side with few hairs, magenta in color.Bracteole two, lateral, linear lanceolate and 5 mm in length, Calyx campanulate, 8 mm, teeth five with bristle hairs, prominent ribs along with the length of each teeth, magenta in color.Corolla bilabiate, (2 upper + 3 lower), lower 3 mm, upper 2.5 mm, lobes obovate, rounded or truncate with tooth at apex, tube 10 mm, curved more or less at right angle of calyx, glabrous, purple hairs at mouth and inside throat.Stamens didynamouse, epipetalous, inside the throat, anther sac black, filament translucent white, dorsifixed, longer 2 mm and shorter 1.5 mm long.Ovary oblong, glabrous, green, 2.5 mm, style 5 mm, glabrous, pale white, stigma 1 mm with minute papilla.Fruit a capsule, capsule ellipsoid oblong, flat, 5.5 mm x 3 mm, shining black, impressed midrib at both side, persistent style at tip, cleft longitudinally from lateral side.Seeds are pale brown, numerous, triangular-oblong, wavy grooves & ridges on surface, 0.4 mm in length.An annual, erect, herbaceous root parasite found on Lepidagathis trinervis.Stem 06 -15 cm tall, un-branched or branched at middle, teret, glabrous, soft, and green or green with reddish tinged.Leaves reduced, alternate, sessile, adjacent to mother axis, scaly, thick, ovate-lanceolate, acute, lower ones acuminate, margin ciliate, concave inside, 08-10x2-2.5mm, and magenta-green, upper ones passing into floral bract.Flowers in terminal spike, 3.5-4 mm in diameter at bilateral axis, bracteate and bracteolate, bracts 4x 1.5mm or slightly shorter than calyx tube, similar to leaves; bracteole two, lateral, linear-lanceolate, length 2-3x1 mm or half to the calyx tube.Calyx campanulate, 6 mm, lower part green, upper part reddish, teeth 4, acute, sparsely pubescent outside, glabrous inside, a longitudinal rib along with each teeth.Corolla bilabiate (2 upper + 3 lower), lower 2.5 mm and upper 2 mm long, tube 7-8 mm, curved more or less at right angle of calyx, long retrorse hair at distal end, glabrous at proximal, hairy at mouth and inside throat, lobes 2-2.5 mm, obovate, rounded or truncate, toothed, white or purplish-white, glabrous both side.Anthers 4, didynamous, longer 1.5 mm shorter 1 mm long, epipetalous and inside the tube, anther sac black, filament translucent white, dorsifixed.Ovary oblong, glabrous, pale green, 2 mm, style long, slender, cylindrical, 4 mm, stigma leafy with minute glutinous papilla.Fruit a capsule, capsule oblong, ellipsoid, flat, 3-4 x 1.5 mm, tipped with persistent style, longitudinal grooves at middle on both side, blackish brown when dried.Seeds numerous, very minute, wavy grooves & ridges all over, light brown or pale brown 0.2 mm long, more or less triangular.Flowering and Fruiting: In rainy season Field Note: Although the Santapau has reported it from Lepidagathis bandraensis and Hygrophila serpyllum I have found it on the roots of Lepidagathis trinervis another sp. of Lepidagathis commonly found in the area.This is a new report of another host.The corolla becomes purple after wilt or falls or plucking.Collection Site: Plant was collected from Andolai (A Small Rain Water Pond) Hill, located at Kabootaro ka Chauk Osian-Jodhpur, Rajasthan.The new site was geo tagged by Google earth (Fig. 1).Specimen examined: Jodhpur, J.N.V. University, Bhandari 1135.

DISCUSSION
It has been experienced that the habit and plant characters viz.height, color, vestiture, and floral characters are important to distinguish the var.minor from its type var.gesnerioides.Hence the following are the discussion on the herbarium specimen, habit and morphology of different plant organs: Herbarium specimen: Herbarium specimen in both varieties become black after preservation and looks same which superficially not beneficial to differentiate both varieties until unless simultaneous comparing of size of all the floral parts and vestiture on them (Fig. 4 &  Habit (Fig. 2): Both the varieties are clearly distinguishable from one another on the basis of height, color of plant and host specificity.The type var.gesnerioides has dark magenta color all over and 20-50 cm tall and characteristically found on roots of Euphorbia caducifolia Haines, although according to Saldanha (1963) [12] it's also reported on Lepidagathis & Dysophylla sp. but I have always found type var. on Euphorbia caducifolia while var.minor has green or reddish-green all over and 6-15 cm tall and found on roots of Lepidagathis trinervis Nees (first report on new host) or Lepidagathis bandraensis Blatter.The Branching pattern was used as a key character by Shetty & Singh (1991) [6] to distinguish both the varieties.According to them the type variety has much branched stem while the var.minor have un-branched stem, similar description was given by Bhandari M.M. (1990) [11] .In my observation I have always found branching in both the variety.Branching may occur from the base which often buried in soil due to the attachment on host root (Fig. 2 C) and not seen until unless digging out the plant, hence looks un-branched.Secondly branching may occur at the middle of stem in both varieties which can easily be seen (Fig. 2 A& B).Flowers: Flowers were found smaller in var.minor (3.5-4 mm in diameter at bilateral axis) comparatively from type var.(5-5.5 mm in diameter at bilateral axis).Another interesting character was observed that after wilt or falls, flowers in var.minor become purple while in type var.they become pale brown or purplish-brown.
Leaves: leaves are reduced in both varieties only the size and color were different.Leaves in var.minor were green or magentagreen with sparsely puberulent or glabrous comparing to dark magenta in type var.with long hairs, also shorter in size from type var.The lower leaves are acuminate in both varieties and successively pass into acute bract.Bract: Bracts were similar accept in color and size, in var.minor bracts were reddish green, shorter and less wide compare to dark magenta with prominent dorsal midrib and larger size in type variety (Fig. 3 B & L).Calyx: Vestiture on calyx teeth was used as key to distinguish both the varieties by Bhandari M.M. (1990).According to Bhandari calyx teeth have few hairs in var.minor compare to long bristle hairs in type.In my observation I have obtain similar finding (Fig. 3 C & M) but also assume that in type variety hairs looks long due to the large size of calyx compare to smaller size of var.minor otherwise in both varieties bristle hairs were observed on teeth.Corolla: Corolla color was mentioned as a key character to distinguish both varieties by all the author viz.Santapau (1949), Bhandari (1990), and Shetty & Singh (1991).The similar observation was found in present investigation for distinguishing both varieties.In var.minor flowers were white with purple shadow compare to lilac